Since the 1960s, Power Plants Have Taken Actions, Such as Switching

Since the 1960s, power plants have taken actions, such as switching to low-sulfur coal and installing scrubbers in their smokestacks, which have significantly reduced the problem of acid rain.Power plants took these actions mainly because:

A) of concern about the environment.
B) large firms in the United States have a history of being "good citizens" and doing what is best for society, even if this reduces their profits somewhat.
C) government policies provided power companies with incentives to take these actions.
D) of concern about the environment and because government policies provided power companies with incentives to take these actions.